| A progress element should have a nested shadow box with a width specified: | |
| | <progress> | |
| | max="100" | |
| | style="-webkit-appearance: none;" | |
| | value="70" | |
| | <shadow:root> | |
| | <div> | |
| | shadow:pseudoId="-webkit-progress-bar" | |
| | <div> | |
| | style="width: 70%; " | |
| | shadow:pseudoId="-webkit-progress-value" |